3D Hollow Porous Spherical Architecture Packed by Iron-Borate Amorphous Nanoparticles as High-Performance Anode for Lithium-Ion Batteries

Bio-Inspired Electrodes with Rational Spatiotemporal Management for Lithium-Ion Batteries

Lithium-ion batteries (LIBs) are currently the predominant energy storage power source. However, the urgent issues of enhancing electrochemical performance, prolonging lifetime, preventing thermal runaway-caused fires, and intelligent application are obstacles to their applications. Herein, bio-inspired electrodes owning spatiotemporal management of self-healing, fast ion transport, fire-extinguishing, thermoresponsive switching, recycling, and flexibility are overviewed comprehensively, showing great promising potentials in practical application due to the significantly enhanced durability and thermal safety of LIBs. Taking advantage of the self-healing core-shell structures, binders, capsules, or liquid metal alloys, these electrodes can maintain the mechanical integrity during the lithiation-delithiation cycling. After the incorporation of fire-extinguishing binders, current collectors, or capsules, flame retardants can be released spatiotemporally during thermal runaway to ensure safety. Thermoresponsive switching electrodes are also constructed though adding thermally responsive components, which can rapidly switch LIB off under abnormal conditions and resume their functions quickly when normal operating conditions return. Finally, the challenges of bio-inspired electrode designs are presented to optimize the spatiotemporal management of LIBs. It is anticipated that the proposed electrodes with spatiotemporal management will not only promote industrial application, but also strengthen the fundamental research of bionics in energy storage.

Competitive Redox Chemistries in Vanadium Niobium Oxide for Ultrafast and Durable Lithium Storage

Niobium pentoxide (Nb2O5) anodes have gained increasing attentions for high-power lithium-ion batteries owing to the outstanding rate capability and high safety. However, Nb2O5 anode suffers poor cycle stability even after modified and the unrevealed mechanisms have restricted the practical applications. Herein, the over-reduction of Nb5+ has been demonstrated to be the critical reason for the capacity loss for the first time. Besides, an effective competitive redox strategy has been developed to solve the rapid capacity decay of Nb2O5, which can be achieved by the incorporation of vanadium to form a new rutile VNbO4 anode. The highly reversible V3+/V2+ redox couple in VNbO4 can effectively inhibit the over-reduction of Nb5+. Besides, the electron migration from V3+ to Nb5+ can greatly increase the intrinsic electronic conductivity for VNbO4. As a result, VNbO4 anode delivers a high capacity of 206.1 mAh g-1 at 0.1 A g-1, as well as remarkable cycle performance with a retention of 93.4% after 2000 cycles at 1.0 A g-1. In addition, the assembled lithium-ion capacitor demonstrates a high energy density of 44 Wh kg-1 at 5.8 kW kg-1. In summary, our work provides a new insight into the design of ultra-fast and durable anodes.

Rational design of walnut-like ZnO/Co3O4 porous nanospheres with substantially enhanced lithium storage performance

Rational fabrication and smart design of multi-component anode materials to achieve desirable reversible capacities and exceptional cyclability are significant for lithium-ion batteries (LIBs). Herein, walnut-like ZnO/Co₃O₄ porous nanospheres were prepared by a facile solvothermal method, which were then applied as a mechanically stable anode material for LIBs. The rationally designed hybridized electrode brings favorable structural features, particularly ZnO/Co₃O₄ porous nanospheres with abundant vacant space and enhanced surface area, enhancing lithium/electron transport and relieving volumetric stresses during the cycling process. Moreover, several in situ hybridized anode materials with electrochemical cooperation further overcome the challenge of capacity decay and conductivity deficiency. The as-obtained ZnO/Co₃O₄ delivered a much better lithium storage performance compared with ZnO, Co₃O₄, and their physical mix. We believe that the novel design criteria will bring opportunities in exploration and promote the practical application of transition metal oxides.

Binary Iron Sulfide as a Low-Cost and High-Performance Anode for Lithium-/Sodium-Ion Batteries

Iron-based sulfides have been deemed as an appealing anode material for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) for their high theoretical capacity and low cost. However, their practical application is limited by drastic volume expansion during cycling and low-intrinsic electronic conductivity. In this work, we report a FeS₂/Fe₇S₈-rGO composite synthesized via a facile solvothermal method as an LIB/SIB anode. The FeS₂/Fe₇S₈-rGO anode exhibits an excellent Li-storage capacity of 514 mAh g^-1 at 2.0 A g^-1 after 3000 cycles and a Na-storage capacity of 650 mAh g^-1 at 0.2 A g^-1 after 250 cycles, respectively. The rGO matrix is deemed responsible for providing good electron conduction and alleviating volume expansion during cycling. The electrokinetic analysis confirms a large portion of intercalational pseudocapacitance as a major contribution to the superior rate performance. In situ X-ray diffraction further reveals details of a combined intercalational and conversional Li-ion storage mechanisms in this Fe-sulfide-based anode. Finally, density functional theory calculations suggest that there exists a synergistic effect at the heterointerface between FeS₂ and Fe₇S₈ to promote electrokinetics.

Nanoporous Composites of CoO x Quantum Dots and ZIF-Derived Carbon as High-Performance Anodes for Lithium-Ion Batteries

Transition-metal oxides are attracting considerable attention as anodes for lithium-ion batteries because of their high reversible capacities. However, the drastic volume change and inferior electrical conductivity greatly retard their widespread applications in lithium-ion batteries. Herein, three-dimensional nanoporous composites of CoO _x (CoO and Co₃O₄) quantum dots and zeolitic imidazolate framework-67-derived carbon are fabricated by a precipitation method. The carbon prepared by carbonization of zeolitic imidazolate framework-67 can greatly enhance the electrical conductivity of the composite anodes. CoO _x quantum dots anchored firmly on zeolitic imidazolate framework-67-derived carbon can effectively inhibit the aggregation and volume change of CoO _x quantum dots during lithiation/delithiation processes. The nanoporous structure can shorten the ion diffusion paths and maintain the structural integrity upon cycling. Meanwhile, kinetics analysis reveals that a capacitance mechanism dominates the lithium storage capacity, which can greatly enhance the electrochemical performance. The composite anodes show a high discharge capacity of 1873 mAh g^-1 after 200 cycles at 200 mA g^-1, ultralong cycle life (1246 mAh g^-1 after 900 cycles at 1000 mA g^-1), and improved rate performance. This work may provide guidelines for preparing cobalt oxide-based anodes for LIBs.